Charged even though account was closed

We fully disconnected and turned in our equipment at the Xfinity store.  Agent gave us a receipt and said our account was closed.  I logged in to delete my bank account info and couldn't get in.  I was then charged for the next month in full even though the account was closed.  Called and waited on hold for an hour and then an agent that could have been AI said that it could see I was due a refund.  then put me back on hold for 30 minutes to "talk to a live agent to process my refund" finally came back on the line and told me that it wasn't sure what was taking so long and it would check.  Came back 15 minutes later and said they were closed.  Gave me a  ticket number and said I would hear back in 3 days or to call again (no way - it is hell to hold and hear the same 30 second music tune followed by how much they appreciate my business).  Didn't hear back so wasted more of my time  going to the Xfinity store today and they said that it will be 4 to 6 weeks to get it processed.  That is ridiculous, are they going to pay me interest on the $254 they stole from my account?